Electric heating – Microwave heating – With control system
Reexamination Certificate
2000-04-07
2001-05-08
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
With control system
C219S722000, C219S724000, C200S050020, C200S050080
Reexamination Certificate
active
06229129
ABSTRACT:
FIELD OF THE PRESENT INVENTION
The present invention relates to a method and apparatus for preventing undesired actuation of a microwave oven when the oven door has not been closed and to prevent tampering by inserting a protrusion within an access entry to overcome a retracted position switch.
PRIOR ART
Many previously known microwave ovens include switches that prevent actuation in the event that the microwave oven door has not been fully closed over the oven chamber. Often times, the oven door includes a probe that extends toward a restricted access opening in the oven body housing. The probe engages an enabling switch when the door reaches the fully closed position. Nevertheless, merely recessing the switch within the access opening provides the opportunity for tampering by insertion of a protrusion, such as a finger, not connected with the door even when the door is in a fully opened positioned.
Other previously known microwave ovens sought to avoid the undesired access of a recess switch by also mounting the switch in a position retracted from the access entry, so that mere insertion of a protruding member in the direction of the access entry opening will not actuate the enabling switch. However, tampering is often accompanied by manipulation of the protrusion from outside of the access entry whereby undesired engagement with the enabling switch may still be accomplished. As a result, the previously known devices have not succeeded in limiting access to an enabling switch where interlocks require complete closure of the oven door before the enabling switch is actuated.
SUMMARY OF THE INVENTION
The present invention overcomes the above mentioned disadvantages by providing a method and apparatus for protecting a switch mounted in a retracted position from an access entry by a directing strap that may be displaced in a direction away from the switch and carrying an inserted protrusion in a direction away from the switch. The obstructing member includes a socket for receiving an end of an inserted protrusion while permitting entry of a probe that may be displaced in a direction toward the switch after closure of the door for engagement of a probe part in the direction of the switch actuator.
In the preferred embodiment, an access entry in an oven body housing cavity receives a probe, attached to the door, and having a protruding member and a lateral prong or lobe that reaches in the direction toward the retracted switch position, for example, lateral to the direction of insertion. Preferably, the probe pivots as it is displaced in the direction of insertion, the pivoting movement being limited in the direction of switch actuation to when the door has been fully closed. A strap is mounted across the access entry to restrict access in the direction of switch actuation and intermediate the boundaries of the access entry. Preferably, a post is positioned at one end of the entry and the strap is mounted adjacent to an opposite end of the access entry. The mount resiliently urges the arm toward the post, but is pivotable in a direction not aligned with a switch actuator for the retracted switch. The arm includes a socket that receives any inserted protrusion and carries the protrusion in the direction of arm displacement.
As a result, any attempt to operate the microwave when the door is opened by attempting to reach the retracted switch position with a protrusion such as a finger, utensil or the like effectively limits the protrusion to a direction that does not approach the direction of switch actuation. As a result, the present invention foils attempts to override enabling switches that have been retracted from an access entry and associated barriers which may be subjected to tampering. Accordingly, the guard of the present invention protects against inadvertent insertion of a finger, tool or other inserted protrusion that is not designed in conformity with the probe that may travel in the direction of switch actuation only when the microwave door has been closed.
REFERENCES:
patent: 3733456 (1973-05-01), Blackburn
patent: 4504719 (1985-03-01), Taylor, Jr. et al.
patent: 4511780 (1985-04-01), Okamura
Brooks & Kushman P.C.
BSH Home Appliances Corporation
Leung Philip H.
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